1. Field of the Invention
This invention relates to a control information assigning method, a control method, a transmitting method, a receiving method, a transmitter and a receiver and more particularly, suitably applied to a cellular radiocommunication system.
2. Description of the Related Art
In a cellular radiocommunication system, an area for providing a communication service has been divided into cells with a desired size and a base station as a fixed station has been provided in each of the cells so that a communication terminal device serving as a mobile station can perform a radio-communication with that base station of which a communication condition is the most preferable.
When a desired communication is carried out in this type of the cellular radiocommunication system, the communication may require high transmitting power or may be carried out even with low transmitting power, depending on the position of the mobile station. Therefore, in the cellular radiocommunication system, the base station and the communication terminal device mutually monitor their receiving power (or the quality of the receiving power) and interchangeably inform each other of the monitoring result so that a feedback loop is formed. As a result, the communication is carried out with the minimum transmitting power required, that is, a transmitting power control is performed. Accordingly, in the cellular radiocommunication system, since the communication can be efficiently achieved with the minimum transmitting power required and consumed power can be reduced as compared with a case in which communications are performed with constant power, the using time of a battery can be extended with a special effect particularly for the communication terminal device.
The cellular radiocommunication system can control the transmitting power by transmitting control information for the power control to the other party of communication, however, it does not have a method of assuredly transmitting the control information to the other party. Therefore, the system is still open for improvement.
In view of the foregoing, an object of this invention is to provide a control information assigning method capable of transmitting control information with good accuracy, a control method capable of precisely performing a control based on the control information, and a transmitting method, a receiving method, a transmitter and a receiver employing them.
The foregoing object and other objects of the invention have been achieved by the provision of a control information assigning method, control method, transmitting method, receiving method, transmitter and receiver.
In the control information assigning method for a control system for performing a prescribed control corresponding to control information by transmitting transmission symbols to which the control information is assigned from a transmitting side and receiving the transmission symbols at a receiving side, present control information and past control information are formed into a pair to be assigned to one of the transmission symbols, so that a prescribed restricted condition is applied to the transmission symbol.
Further, in the control method for a control system for performing a prescribed control corresponding to a controlled variable by transmitting transmission symbols to which the controlled variable is assigned from a transmitting side and receiving the transmission symbols at a receiving side, when the transmission symbol to which a pair of present controlled variable and past controlled variable is assigned is transmitted, the receiving side stores a cumulative controlled variable from an initial state to each symbol, decides a transmission symbol of which the branch metric sum is the minimum out of said transmission symbols received as a received symbol, and performs the control based on the cumulative controlled variable of the decided symbol.
Further, in the transmitting method for a communication system for controlling transmitting power of the local station corresponding to control information by transmitting transmission symbols to which the control information for controlling transmitting power is assigned from a transmitting side and receiving the transmission symbols at a receiving side, present control information and past control information are formed into a pair to be assigned to one of the transmission symbols, so that a prescribed restricted condition is applied to the transmission symbol and the transmission symbol, to which the restricted condition is applied, is transmitted.
Further, in the receiving method for a communication system for controlling transmitting power of the local station according to a controlled variable by transmitting transmission symbols to which the controlled variable for controlling the transmitting power is assigned, from a transmitting side and receiving the transmission symbols at a receiving side, when the transmission symbol to which a pair of the present controlled variable and the past controlled variable is assigned is transmitted a cumulative controlled variable is stored from an initial state to each symbol, a symbol of the received transmission symbols of which the branch metric sum is the minimum is decided as a received symbol, and the transmitting power of the local station is controlled based on the cumulative controlled variable of the decided symbol.
Further, the transmitter for a communication system for controlling transmitting power of the local station based on control information by transmitting transmission symbols to which the control information for controlling the transmitting power is assigned, from a transmitting side and receiving the transmission symbols at a receiving side, comprises a symbol forming means for forming present control information and past control information into a pair and assigning this pair to one of the transmission symbols so as to form a transmission symbol to which a prescribed restricted condition is added and a transmitting means for transmitting the transmission symbol to which the restricted condition is added.
Furthermore, a receiver for a communication system for controlling transmitting power of the local station based on a controlled variable by transmitting transmission symbols to which the controlled variable for controlling the transmitting power is assigned, from a transmitting side and receiving the transmission symbols at a receiving side, comprises a controlling means, when the transmission symbol to which a pair of the present controlled variable and the past controlled variable is assigned is transmitted, for storing cumulative controlled variable from an initial state to each symbol, deciding a symbol of the transmission symbols received of which the branch metric sum is the minimum as a received symbol, and forming a transmitting power control signal based on the cumulative controlled variable of the decided symbol and a variable gain means for setting the transmitting power of the local station to a desired value based on the transmitting power control signal.
The nature, principle and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings in which like parts are designated by like reference numerals or characters.